A blog by Julian Cribb

Early warning of a runaway climate

Global warming is edging perilously close to out-of-control, according to scientific reports from round the planet.

This means that time is running out if we want to preserve our world in a stable, healthy and productive state, capable of feeding and supporting humanity.

The great concern is the dramatic rise, over the last three years, in methane levels in the atmosphere. Methane is a gas with 28 times the climate-forcing power of carbon dioxide. Scientists estimate there may be as much as 5 trillion tonnes of it locked in permafrost and in shallow ocean deposits.

Scientific evidence is amassing that, as the planet warms due to human activity, these vast reserves of greenhouse gas are now starting to melt and vent naturally. The Earth’s past history – in an event 50 million years ago known as the Palaeocene-Eocene Thermal Maximum, or PETM – shows this could unleash runaway global warming by driving up planetary temperatures by as much as 9 or 10 degrees Celsius.

At such temperatures, many scientists consider there is a high risk of the planet becoming uninhabitable to humans and large animals. Certainly it would eliminate agriculture and most food production and unleash the mass migration of hundreds of millions of starving refugees. Runaway heating and nuclear war are the two most likely triggers for human extinction – and it is time everyone took them both a lot more seriously.

Reports of methane escaping into the atmosphere have been growing steadily, ever since a group of students demonstrated the risks by setting fire to venting Arctic gas in 2008. However, scientists report a sudden surge in global methane emissions in the last three years, 2014-16.

The rise in methane has been attributed mainly to human activities like cattle raising, rice farming, gas and coal extraction – but there is now disturbing evidence that more gas is emerging from Arctic soils as the permafrost melts, and from the seabed where methane has been trapped as ice for millions of years.

Russian scientists have reported the discovery of thousands of potential ‘methane-bombs’ – frozen gas-filled mounds known as pingos – across Siberia, primed to explode as the ground thaws out.

Swedish scientists have observed the waters of the Artic oceans ‘fizzing like soda water’ as the ocean currents warm, causing frozen seabed methane to turn back into gas and erupt.

The essential arithmetic says that so far humans have released about 2 trillion tonnes of carbon, which has warmed the planet by one degree C. By 2040, we are on track to release another trillion tonnes and push the planet’s temperature up by 2 degrees or more.

This we can possibly control, by cutting back on our use of fossil fuels and by ceasing to burn coal. However, there is no way we can control the methane venting naturally from the seabed and permafrost once it starts – and there may be 5 trillion tonnes of it. This phenomenon is known to scientists as the ‘clathrate gun’. If it fires, the fate of the entire human species is at risk.

Technical difficulty in measuring the Earth’s natural methane emissions and estimating the size of its reserves has until now led to the methane threat being discounted, or downplayed, in warnings about dangerous climate change by the Intergovernmental Panel on Climate Change and other agencies.

That time is over. We are now receiving early warning of a major methane release. If it runs out of control, there will be nothing humans can do to prevent the planet overheating quite rapidly.

This makes it more urgent than ever that governments and corporations of the world unite to cut human carbon emissions. The recent Climate Turning Point report says the world has until 2020 – just two and a half years – to start lowering global carbon emissions by cutting fossil fuel use. Time is running out – and the methane gun makes matters all the more urgent.

This means that countries like America and Australia have to cease their dangerous do-nothing policies and stop mining coal, countries like India and China need to stop building coal-fired power stations immediately – and every country needs to make a far larger effort to scale back its carbon emissions from transport, agriculture and industry.

Denialists and do-nothings defend fossil fuels on the grounds ‘they are good for the economy’. They appear not to understand that you first have to have a human civilization or a human species in order to have an economy.